Ink-jet printing generally involves ejecting ink droplets from orifices in a print head onto some type of receiving media to form a desired image. Printers for use in such printing may use, for example, solid ink or phase change ink. Solid ink or phase change ink printers may receive ink in a solid form, sometimes referred to as solid ink sticks. The solid ink sticks may be inserted through an insertion opening of an ink loader for the printer, and may be moved by a feed mechanism and/or gravity toward a heater plate. The heater plate melts the solid ink impinging on the plate into a liquid that is delivered to a print head assembly for jetting onto a recording medium. The recording medium may be, for example, paper or a liquid layer supported by an intermediate imaging member, such as a metal drum or belt.
A print head assembly of a phase change ink printer may include one or more print heads, each having a plurality of ink jets from which drops of melted solid ink are ejected towards the recording medium. The ink jets of a print head receive the melted ink from an ink supply chamber (or manifold) in the print head which, in turn, receives ink from a source, such as a melted ink reservoir or an ink cartridge. Each ink jet includes a channel having one end connected to the ink supply manifold. The other end of the ink channel has an orifice or nozzle for ejecting drops of ink. The nozzles of the ink jets may be formed in an aperture, or nozzle plate that has openings corresponding to the nozzles of the ink jets. During operation, drop ejecting signals activate actuators in the ink jets to expel drops of fluid from the ink jet nozzles onto the recording medium. By selectively activating the actuators of the ink jets to eject drops as the recording medium and/or print head assembly are moved relative to each other, the deposited drops can be precisely patterned to form particular text and graphic images on the recording medium. An example of a full width array print head is described in U.S. Patent Application Publication No. 2009/0046125, which is hereby incorporated by reference herein in its entirety. An example of an ultra-violet curable ink that can be jetted in such a print head is described in U.S. Patent Application Publication No. 2007/0123606, which is hereby incorporated by reference in its entirety.
One difficulty faced by fluid ink jet systems is wetting, drooling, or flooding of inks onto the print head face plate. This may occur as a result of ink contamination of the print head face plate. FIG. 1 illustrates a face plate 5. As shown, the face plate 10 of the print head face plate 5 is displayed with the ink nozzles 15 located along the center strip of the face plate 10. The image shown displays an example of flooding, where ink has drooled 20 out of the nozzles 15 to result in print head failure. The contaminated face plate can cause or contribute to non-firing or missing drops, undersized or otherwise wrong-sized drops, satellites, or misdirected drops on the recording medium, and thus may result in degraded print quality.
Several material-based approaches have been proposed to address this problem, such as, for example, adding hydrophobic properties to a coating for use as a layer on the print head face plate. Hydrophobicity may be imparted, for example, by integrating fluorine content into the material, and coating the material onto the print head face plate. However, the coating process may not be a straightforward procedure. For example, the coating may be created by sol-gel polymerization, and the coating is ideally applied when the coating is in the sol phase. Gelation may occur upon standing or with heat treatment. However, the fluorinated material may not have a reliable pot life, and could gel before the fluorinated material could be applied as a wet layer on the substrate. For example, the coating solution may sometimes gel instantaneously or within a few minutes of preparing the coating solution.
As such, there is desired a formulation composition that has a reliable pot life, such that it can be applied to, for example, a print head face plate as an ungelled wet layer, while still producing, upon curing, an antiwetting coating for the ink jet print head that maintains high drool pressure and low ink adhesion over the life of the part.